Apparatus and Method for Harvesting and Dewatering of Microalgae Biomass

Abstract

An apparatus and method for separating, harvesting and primary dewatering microalgae biomass from a microalgae solution by destabilization thereof with addition of kinetic energy thereto is disclosed. The method to overcome the energetic barrier preventing a fluid-solid separation comprises injecting the microalgae solution in an electrolytic system comprising an electrocoagulation reactor generally comprising an anode module and a cathode module, the anodes and the cathode(s) being adapted to be electrically connected to perform electrolysis, thus separating, harvesting and primary dewatering microalgae biomass. Such process is generally achieved by providing a DC electric current, between the anodes and the cathode(s), to perform the separation of the bio mass in the solution, in preparation the following process steps of for liquid / solid separation and primary dewatering.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present patent application claims the benefits of priority of U.S. Provisional Patent Application No. 61 / 706,917, entitled APPARATUS AND METHOD FOR HARVESTING AND DEWATERING ALGAL BIOMASS, and filed on Sep. 28, 2012, at the United States Patent and Trademark Office, the content of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention generally relates to a method and system for removing contaminants from wastewater using electrolysis, and more particularly to an electrolysis method and system that may be used for harvesting and for dewatering microalgae biomass, as well as extracting contents from microalgae.BACKGROUND OF THE INVENTION[0003]Sustainable development focuses on operational efficiency while promoting the minimization of environmental, social and economic impacts, demands a better utilization of our natural resources, especially the non-renewable ones. It is evident tha...

AI Technical Summary

Benefits of technology

The present invention provides a method for quickly and easily installing and expanding a modular electrocoagulation and / or electro-floatation system for harvesting and primary dewatering microalgae solution and extracting contents from microalgae cells. The method includes a quick loading anodes cartridge and cathode(s) that can be easily replaced, which makes maintenance and repair of the system more convenient.

Problems solved by technology

It is evident that the continued use of fossil fuels is no longer viable due to the depletion of global resources (Brennan and Owende, 2009).

Also, as other biofuel sources (e.g. corn or sugar cane) the culture of microalgae does not necessarily compete with food supply.

Today, microalgae harvesting and dewatering remains a major obstacle to industrial-scale production of biofuels (Pienkos Darzins, 2009; Uduman et al, 2010).

Although, several technologies for the separation of microalgae biomass are known, they still require large capital investments and / or large operational expenditures.

The challenge of cost-efficient harvesting and dewatering of microalgae resides in their small size and low concentration in the culture medium.

Existing harvesting and dewatering technologies such as centrifugal recovery and filtration require a relatively high amount of energy.

The negative charge at the surface of microalgae creates repulsive forces between negatively charged particles, which cause them to remain suspended in solution.

Moreover, many species of microalgae have a natural tendency to float since their cells contain relatively large quantities of low density lipids, which accelerates the floatation process.

Chemical coagulation has been successfully used for decades, but it has a few shortcomings, which include risks for health and safety posed by the handling of hazardous chemicals and costs associated with the handling and treatment of the generated sludge that may contain relatively high levels of heavy metals.

Moreover, traditional coagulation and flocculation techniques may use chemicals that are proven to be less effective in saline conditions.

Currently, this is mainly done using activated carbon or discoloration agents, which are both expensive techniques.

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